Thomas montresor baldwin



momodel') T. M. BALDWIN.

APPARATUS PQR SEPARATING GOLD PROM WASH. N0 579 945 Patented Apr. 6,1897.

UNITED STATES PATENT OFFICE.

THOM AS MONTRESOR BALDXVIN, OF DUNEDIN, NEHV ZEALAND.

APPARATUS FOR SEPARATING GOLD FROM WASH.

SPECIFICATION forming part of Letters Patent No. 579,945, dated April 6,1897.

Application filed December 4,1893. Serial No. 492,676. (No model.)Patented in New Zealand August 20,1892,No. 5,728; in New South WalesOctober 5, 1892, No. 4,018, and in Victoria October 15, 1892,1l0.10,044.

To all whom it may concern:

Be it known that I, THOMAS MoNTnEsoE BALDWIN, of Dunedin, in theProvince of Otago, New Zealand, have invented a new and usefulImprovement in Apparatus for Separating Gold from XVash', (for which Ihave obtained Letters Patent of Victoria, No. 10,04l, dated October 15,1892; of New South lVales, No. 4,018, dated October 5, 1802, and of NewZealand, No. 5,728, dated August 20, 1892 and I do hereby declare thefollowing to be a full, clear, and exact description thereof.

Figure 1 is a longitudinal section of the apparatus. Fig. 2 is a plan ofa sluice-box; and Fig. 3 is an enlarged view, in vertical longitudinalsection, of part of the bottom of a sluice-box.

a are standards carrying a shaft 6, free to revolve in bearings c on thesaid standards a. Rotary motion is given to the said shaft by belt orother gear in any convenient way. d are arms firmly secured to the saidshaft. Z) 6 e e are cylindrical concentric sieves or screens secured tothe said arms (Z.

f is a chute through which the wash from' which the gold is to beseparated is run into the central sieve or screen 6. The sieve or screen6 is conveniently made of boiler-plate or of iron bars placedlongitudinally and separated, say, a quarter of an inch, more or less,as required, and extends at each end beyond the surrounding sieves, thatportion between the arms, if made of boiler-plate, being perforated withslots one-quarter of an inch by two inches, more or less, as required,while the portions beyond the arms are not perforated and serve to carrythe material into the screen at the upper end and into the boxes andtail-race at the lower end. The sieves or screens 6' and c are made ofwire having, respectively, about one-eighth-inch and onesiXteenth-inchmeshes.

h is a fixed case surrounding the sieves or screens and having anaperture 2' at its lower end.

Although the sieves or screens have been shown secured to and revolvingwith a shaft, the shaft may advantageously be dispensed with, and thesaid sieves or screens may be provided with circular rails and becarried on pulleys in any well-known manner, so that if it is desired towash the gold-containing materials in the sieves or screens a pipe maybe carried into the central sieve or screen 6.

j is the tail-race, into which the wash which will not pass through theperforations or slots in the sieve or screen e is delivered through thechute k, and into which finally passes the wash from the sluice-boxes jand 7' and the casing 71 The sieves or screens c and c communicate withthe sluice-boxesj and j by means of the chutes 71) and 71: The saidsluice-boxes are made wider at the delivery end than at the receivingend, so that the pressure of water is lessened by being spread over agreater area. The bottom of each sluice-box is fitted with transverseribs Z, which carry a false bottom m, made in one or more pieces. Thetapered form of the false bottom allows of its being easily withdrawnfrom the lower or delivery end. The false bottom is made with transverseapertures 92 between each pair of ribs, and the said apertures decreasein width from the receiving to the delivery end. The width of theapertures n at the upper or receiving end of the sluicebox j is aboutone-quarter of an inch, or, in accordance with the size of the materialscreened, about three-sixteenths in the middle and about an eighth of aninch at the lower or delivery end. The sluice-box aperturesf are aboutone-eighth of an inch wide at the upper or receiving end, about threethirty-seconds of an inch wide at the middle, and about one-sixteenth ofan inch wide at the lower or delivery end.

o is a tank having the end where the wash enters it sloping down towardthe bottom. 19 is the overflow, which can be used to convey water to thesluice-boxes j and 3' 0' is a movable partition placed across the saidtank between the inlet and the overflow and .descending below the levelof the water in the tank, so that any float gold is prevented frompassing direct from the inlet to the overflow and must sink into thecollecting-box g beneath the said tank. The said box qis freely open tothe tank 0 above and is fitted at the bottom with numerous tubes 0", sayabout three-eighths of an inch in diameter, which convey the materialonto mercury in a tray 3. The tubes q may be inclined from the verticalin a circumferential direction. is the overflow edge of the tray,leading to the tail-race The wash enters the sieve or screen 6 from thechute f, and any material larger than the size of the perforations orslots passes out of the said screen through the k chute to the tailracej, while all the smaller material passes through the perforations orslots in the said sieve or screen into the sieve or screen 9. Here anyparticles of material greater than the size of the mesh pass by thechute it into the sluice-boxy, while the remainder of the wash passesthrough the meshes into the sieve or screen 6 Here the particles greaterthan the size of the mesh pass by the chute k into the sluice-boxfi, theremainder passing through the mesh into the case h, and thence by theaperture 7 into the tank 0. The gold in the wash passing into thesluiceboXes is collected in the spaces between the ribs. The lightergravel or material flows away, as there is no suction of water into thesaid spaces. The particles of material in the wash which enter the tank0 pass into the box q, and thence through the tubes r onto the mercuryin the tray 3. The pressure of The gold is caught by the mercury, whilethe sand and fine particles and water glide over the surface and arecarried off through the tail-race.

I claim--- 1. A sluice-box which Widens gradually toward the dischargeend, said box having upon its bottom transverse ribs upon which rests aremovable false bottom, said false bottom also widening toward itsdischarge end, and having between the supporting-ribs a series ofprogressively narrower transverse aper tures, substantially asdescribed.

2. In a gold-separator, the combination with a series of inclinedconcentric cylindrical screens, each screen being successively shorterthan the next screen inside the same, of collecting sluice-boxes at thelower ends of the screens, each sluice-box widening toward its dischargeend, and having transverse ribs upon which is carried a'false bottomhaving transverse apertures between the ribs, said apertures growingprogressively narrower toward the discharge end, substantially asdescribed.

In testimony whereof I have hereunto set my hand this th day of October,A. D. 1893.

THOMAS MONTRESOR BALDWIN.

\Vitnesses:

S. B. HOWLETT, P. DUNCAN.

